Mycology laboratory diagnostic capacity for invasive fungal diseases in public hospitals in Vietnam

Abstract This was a cross-sectional study on the availability of laboratory infrastructure and capacity for the diagnosis of invasive fungal diseases in 24 public hospitals in Vietnam in 2023. Among the hospitals surveyed, 66.7% (14/21) had specialized personnel assigned for mycology testing, and 95.8% (23/24) had a separate microbiology laboratory space. Microscopy and culture methods are available in nearly all laboratories for isolate identification. Antifungal susceptibility testing is only performed for yeasts in 16/24 (66.7%) laboratories. Non-culture methods are hardly used in laboratories. Strengthening local laboratory capacities is essential to meeting health needs in these endemic regions.


Introduction
Invasive fungal diseases (IFDs) pose a significant burden on global healthcare, resulting in an estimated 3.8 million annual deaths worldwide. 1This burden of disease is now being compounded by the emergence of antifungal resistance, worsening treatment outcomes, and increasing mortality rates. 2 Accurate diagnosis is the key to effective medical treatment, and, therefore, to relieving the burden of IFDs.Laboratory diagnosis of fungal diseases includes classic microscopy and culture-based methodologies, serology, and molecular testings.The availability of all of these methods varies by geographical regions, with limited access in low-and middleincome countries [3][4][5] alongside a lack of formal training in medical mycology. 6ietnam has a population of 100 million and a high burden of HIV (249 000 people living with HIV in 2023) and tuberculosis (172 00 new cases in 2022)-both highly relevant to fungal infections. 7 , 80][11] We therefore investigated the laboratory infrastructure and diagnostic capacity for fungal diseases.

Materials and methods
This was a cross-sectional study of public hospitals in Vietnam, conducted from July to September 2023 using a convenience sampling method.We pre-identified the largest provincial general hospitals and sent them invitations to participate in this study via paper forms.
The study questionnaire collected data on (1) hospital size, (2) mycology laboratory infrastructure, (3) capacity for fungal identification and susceptibility testing, and (4) participation in an external quality assessment (EQA) programme and research.A draft questionnaire was developed by V.Q.D., J.B., and V.N.H. and piloted with doctors from Hanoi Medical University Hospital (not included in the final analysis) before being distributed to the targeted hospitals.The forms were completed by the laboratory staff in hospitals and validated by the head of the laboratory.The collected data were transferred to an electronic database using the Qualtrics platform.Data were processed and analysed using RStudio (version 1.2.5019).Categorical data were presented as frequencies and percentages, while numerical variables were presented by median and interquartile range (IQR).Collected data were measured against the features of a model state of fungal diagnostics, as outlined in the Global Action Fund for Fungal Infections (GAFFI) roadmap and WHO Fungal Priority Pathogens List, to identify gaps for future improvement. 12 , 13

Results
A total of 24 hospitals participated in the survey, corresponding to a response rate of 40% (24/63).This included 8/24 (33.3%) central hospitals and 16/24 (66.7%) provincial/municipal hospitals.The median bed capacity of central hospitals was 1500 (IQR 1162-2000) and for provincial/municipal hospitals was 900 (IQR 637.5-1200).A total of 95.8% (23/24) had a distinct microbiology laboratory space, and 43.4% (10/23) had a separate space exclusively for mycology (Table 1 ).Few laboratories were involved in research, and storage of isolates was uncommon.Only 20.8% (5/24) indicated that they stored yeast isolates for longer than one year, dropping to 12.5% (3/24) for moulds (Table 1 ).Subgroup analysis suggested that laboratories interested in research were more likely to store clinical isolates.Among 12 hospitals with reports of fungal isolates in 2022, the most commonly identified pathogens were Candida spp.(including 1288 C. albican isolates, 227 C. tropicalis isolates, 126 C. parasilosis isolates, 8 C. auris isolates , and 8 Candida spp.isolates), Aspergillus fumigatus (24 isolates), and Cryptococcus neoformans (9 isolates) (data not shown).A detailed breakdown of the availability of different diagnostic tests 'on-site' is shown in Table 2 .
The main methods for identification of yeasts were biochemical phenotypic methods using automatic instruments (58.3%), followed by chromogenic agar media for rapid Candida identification (29.2%), and benchtop biochemical methods like API AUX or ID (8.3%).The identification of moulds was only based on the morphological characterization.
Relative to an ideal fungal diagnostic system, prominent gaps identified across participant hospitals included a lack of laboratories with spaces exclusively dedicated towards mycology testing, lack of antifungal susceptibility testing, and an absence of serological and molecular tests.Limited use of India ink staining for cryptococcal diagnosis, MALDI-TOF MS, and PCR was identified as important gaps inhibiting access to timely and accurate fungal diagnosis.Further, limited participation in external mycology quality assessment services, limited participation in research activities, and limited demand for education and training to promote fungal diagnosis capacity were notable gaps.

Discussion
In Vietnam, fungal infections pose a significant public health concern, with the majority of the burden being attributable to tuberculosis and HIV/AIDS. 11Here, we present the first national survey on the capacity for IFD diagnostics, which adds significant depth to the previous study by Salmonton-Garcia et al. 4 Accurate identification of fungal species is important for selection of suitable antifungal therapy.In 2022, WHO published the Fungal Priority Pathogens List, calling for action to improve the prevention, diagnosis, and treatment of these priority pathogens.The GAFFI list of core diagnostic tests that should be present in a reference lab, including direct microscopy, antigen detection, molecular tests, fungal culture, and identification, forms the basis of our recommendations. 12n ideal fungal diagnostic system offers access to affordable diagnostic tests for fungal infections for timely and accurate diagnosis, incorporating antifungal susceptibility testing.It should support ongoing surveillance to inform clinical practice, helping clinicians screen for and treat life-threatening IFDs to improve patient survival. 3Our findings revealed a significant departure from this model system of fungal diagnostic capacity, with all of the participating laboratories lacking sufficient fungal testing capability to act as independent mycology laboratories, with a particularly notable lack of essential antigen detection and molecular tests. 12 , 13nother major issue was the lack of participation in regular external mycology quality assessment.This is a useful marker of competence of a laboratory, 14 ensuring patients have access to high quality diagnostics. 5he disproportionate burden of IFDs on immunocompromised individuals, increasing emergence of MDR fungal species with their detrimental impacts on treatment outcomes and mortality, and the growing rate of at-risk populations stress the importance of reliable health system capacity for fungal disease diagnosis.There is a pressing need to close this gap between the current national system's capacity for fungal diagnosis and the ideal standard.Timely access to accurate and quality fungal diagnostics promotes the rational use of antifungal agents for effective treatment and reduces unnecessary empiric antimicrobial use in line with the WHO agenda on antimicrobial resistance. 13 , 15his first national survey on IFD diagnostics reveals substantial diagnostic gaps in Vietnam.None of the labs surveyed could perform the full range of 'core tests' outlined by GAFFI.Participation in external mycology quality assessment programmes was relatively low compared to other Asian countries.It is evident that laboratory capacity is not currently keeping pace with the growing disease burden of IFDs.

A c kno wledg ements
The study protocol was approved by the Institutional Review Board of the Hanoi Medical University (917/GCN-HDDDNCYSH-DHYHN).

Table 1 .
Basic characteristics and subgroup analysis by level of hospital.

Table 2 .
Diagnostic services a v ailable on-site.